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In this section, exposure pathways are evaluated to determine whether people accessing orliving near IAAAP could have been (past scenario), are (current scenario), or will be (futurescenario) exposed to installation-related contaminants. In evaluating exposure pathways,ATSDR determines whether exposure to contaminated media has occurred, is occurring, orwill occur through ingestion, dermal (skin) contact, or inhalation of contaminants. Whenexposure to contaminated media occurs, the exposure pathway is regarded as "complete." Todetermine whether completed pathways pose a potential health hazard, ATSDR comparescontaminant concentrations to health-based comparison values. Comparison values arecalculated from available scientific literature on exposure and health effects. These values,which are defined for each of the different media, reflect the estimated maximum contaminantconcentration for a given chemical that is not likely to cause adverse health effects, given astandard daily ingestion rate and standard body weight. If contaminant concentrations areabove comparison values, ATSDR further analyzes exposure variables (for example, durationand frequency) and the toxicology of the contaminant. This exposure evaluation process is summarized in Figure 3.

Contaminants have been detected in on-site groundwater, surface water, soil, sediment, andlocal biota and in off-site groundwater and surface water. RDX is the primary contaminant ofconcern, although other explosive chemicals, VOCs, SVOCs, and some metals were detectedat low concentrations. ATSDR evaluated available on- and off-site information on potentialcontamination in groundwater (Figures 4 and 5), surface water, soil, sediment, and localagricultural produce and deer to determine if these media pose any past, current, or futurepublic health hazards. ATSDR concluded that public exposures to groundwater, surface water,soil, sediment, and local biota are not likely to result in adverse human health effects because,when detected, contaminant concentrations were too low to pose a health hazard and/or werenot accessible to the general public. Information on these exposure pathways is summarized inTable 2 and the following text. A detailed evaluation of potential public health hazardsassociated with all 33 RI/FS sites is summarized in Appendix A. Figure 6 shows the locationsof these 33 RI/FS sites, in addition to 11 other no further action sites identified during the PA/SI.

The following discussion evaluates community concerns about potential human exposure viacontaminated groundwater, soil, sediment, and local biota. This section states each concern,presents a brief summary of ATSDR's conclusions, and describes in more detail any identifiedexposure pathways and the basis for ATSDR conclusions. ATSDR's conclusions regarding thepast, present, and potential future exposures to various environmental media on and in thevicinity of IAAAP are based on the evaluation of data gathered from remedial siteinvestigations, groundwater monitoring data, on- and off-site drinking water well data, and theobservations compiled during site visits.

Concern: Groundwater

Could exposure to RDX or other contaminants in groundwater result in adversehuman health effects for residents of neighboring communities or for formerresidents, employees, or visitors of IAAAP?

Conclusions

After detailed review of the available data, ATSDR has drawn several conclusions regardingpast, present, and possible future exposures to contaminated groundwater at IAAAP. Theseconclusions are outlined below.

Present and Potential Future Exposures

There is no on-site exposure to groundwater. IAAAP does not, and will not, usegroundwater as potable water. IAAAP drinking water, supplied by theBurlington Municipal System, meets (and will continue to meet) federal and state drinking water standards (e.g., MCLs).

In 1993, off-site contamination of private drinking water wells with explosives was confirmed and the IAAAP offered to connect residents in the contaminated area to the Rathbun Rural Water System. One hundred and fifty-four residences accepted the Army's offer, while 15 households declined. Those 154 residences who connected to the Rathbun Rural Water System eliminated the present and potential future exposure pathways via contaminated drinking water. Of those who declined, 14 households use uncontaminated private wells that are periodically monitored by the Army. The remaining household knowingly uses a private well that does not meet federal and state drinking water standards. The Army has repeatedly advised the household to abandon the well, but the fully-informed residents continue to drink well water and knowingly accept any associated risks.

ATSDR concludes that present and potential future exposures to RDX-contaminated groundwater, both on and off site, are not likely to occur or resultin health effects.

Past Exposures

Past activities at IAAAP affected groundwater underlying and south of militaryproperty. RDX is the main contaminant of concern.

Five on-site production wells were active from 1941 until 1977, but these wellswere never used for drinking water purposes so people living, working, orvisiting IAAAP were not exposed to RDX-contaminated groundwater.

People living south and southeast of IAAAP may have been exposed to RDX-contaminated drinking water in the past. The first documented detections ofRDX in two drinking water wells was in 1992. The initial date of contaminationremains unknown, but these two wells did not contain RDX-contaminatedgroundwater in 1985.

Local residents living south and southeast of IAAAP were connected to theRathbun Rural Water System after groundwater contamination was detected in1992.

The two main aquifers affected at IAAAP are the loess/till aquifer (drift aquifer) and theunderlying upper bedrock aquifer. The majority of contaminant movement takes place in thedrift aquifer. The groundwater table in the drift aquifer generally occurs within 10 feet of theground surface, and often less. Shallow groundwater flow closely parallels the ground surface. Thus, shallow groundwater flow throughout the installation is from high points, including mostof the Line and Yard areas, toward surface drainages, particularly the larger streams such asSpring, Brush, and Long Creeks and the Skunk River. The water in the upper bedrock aquifergenerally flows to the south and east, toward the Skunk and Mississippi Rivers. In some on-site areas, including the southwestern part of IAAAP, the upper bedrock aquifer is exposed atground surface and discharges into surface waters. Elsewhere at IAAAP, the upper bedrock aquifer lies at depths of more than 50 or 100 feet.

Groundwater Use

IAAAP has five on-site production wells, none of which have ever been used for drinkingwater purposes. Four of these five wells were installed in 1941 and remained functional until1977, when IAAAP began using public water from the city of Burlington.2 Three of these on-site wells were never used, apparently due to low recharge rates. The fourth well served (butwas never used) as an alternate water source for the water treatment facility (Hicks, 1999). In1981, IAAAP installed a fifth on-site well to provide sanitary water to the facility buildings. Itcurrently supplies sanitary water to the MILVAN Facility and there are no plans to abandon it. Because none of the on-site wells ever supplied IAAAP drinking water, exposure to on-siteRDX-contaminated groundwater never occurred.

IAAAP does not control the use of groundwater once it migrates off property boundaries. Priorto the early 1990s, all local residents south and southeast of the installation used private wellsfor drinking and irrigation. After groundwater contamination was documented in 1992, allpotentially-impacted households were afforded the opportunity to connect to the Rathbun RuralWater System at the Army's expense (Allison, 1999a). By the fall of 1994, 154 residentsliving south and southeast of IAAAP were connected to the Rathbun Rural Water System. Rathbun water is filtered and treated to meet all federal and state drinking water standards. The closest public or municipal wells are located over 3 miles away from IAAAP property andare not at risk from installation-related contamination.

According to Army accounts, 15 households refused the Army's offer to connect localresidences to the Rathbun Rural Water System (Allison, 1999a). Fourteen of these 15households draw water from uncontaminated aquifers so no past or current exposures tocontaminants have occurred. The fifteenth household obtains its well water from an aquiferimpacted by RDX. The Army did connect this residence to the Rathbun Rural Water System in1993, but the individuals at the residence refused to abandon the private well. Instead, theresidents connected the contaminated well to another structure on the property. The well(identified as Well 2 in the Groundwater Quality section below) provides all potable water tothis other structure. Despite repeated Army outreach efforts and recommendations to abandonthe well, the household chooses to continue to use the well for domestic purposes and toknowledgeably assume any associated risks with drinking this water. Except for this onehousehold, no one is exposed to potentially harmful levels of contaminants because all localdrinking water meets (and will continue to meet) federal and state drinking water standards. Ithas, however, been reported to ATSDR by local residents that some other residents' wells arestill used for irrigation and some residents now apparently utilize some of those wells for bathing and other purposes not directly involved with drinking or cooking.

Groundwater Quality

ATSDR's records search found that in the early 1950s, IAAAP discharges were suspected ofcontaminating a few shallow wells located close to Brush Creek outside of the IAAAPproperty. ATSDR was unable to locate any studies or data to confirm or quantify these events. This problem was reportedly (IAAAP records) alleviated by making changes in disposalmethods, including treatment and filtration of process waters prior to discharge.

Quantitative groundwater monitoring began at IAAAP and off-site locations in the 1980s. RDX is the only contaminant that has been detected above ATSDR comparison values in off-site groundwater. Underlying different sites within IAAAP, however, on-site groundwatercontained contaminants variably exceeding proposed site cleanup goals, including:

Because contaminants underlying IAAAP are inaccessible and groundwater is not used as asource of drinking water, there is no exposure (past, present, or potential future) to thesecontaminants on site (Marquess, 1997; Mason and Hanger Corporation, 1997).

In 1985, the Army sampled off-site private wells adjacent to IAAAP's southern boundary. Contaminants were not detected in any off-site wells and all well water met federal and statedrinking water standards (AEHA, 1985).

Off-site contamination was first detected above ATSDR comparison values in September 1992during Phase I of the RI. Groundwater samples were collected from six residential wells (Well1 through Well 6 in Table 1) located on the south/southeast border of IAAAP in the BrushCreek watershed. Well 1 and Well 2 contained explosives at levels (15.5 parts per billion[ppb] and 27.5 ppb, respectively) above the available screening value, EPA's lifetime healthadvisory limit (HAL), of 2.0 ppb for RDX. These wells were re-sampled on March 15, 1993;the presence of RDX at similar levels in the same wells was confirmed (ACE, 1997b,c).

In response to the findings of off-site contamination during the Phase I RI, the Army conductedan extensive off-site sampling and analysis program. This program investigated all residenceslocated in areas of suspected groundwater contamination and in the watersheds associated withsurface water leaving the IAAAP. The Phase II RI, beginning in April 1993, included thesampling of 54 residential wells in the IAAAP vicinity. Three wells (Well 7, Well 8, and Well9 in Table 1) contained RDX above the HAL of 2.0 ppb. Two of these residences are locatedat the extreme southwest boundary of IAAAP, near the town of Augusta, on a tributary of theSkunk River. The third residence is located along the Brush Creek watershed adjacent to thefirst two homeowners whose wells tested positive for RDX. Because all reported RDX valueswere near the HAL of 2.0 ppb, the wells were re-sampled to corroborate initial samplingresults. The second round of well samples at the three affected residences showed RDX contamination at similar levels (ACE, 1997b,c).

The Army's most recent sampling event, a supplemental groundwater investigation conductedin August 1998, indicates that RDX concentrations have decreased since 1993. Two wells(Wells 1 and 2) currently contain detectable concentrations of RDX (6.0 ppb and 6.2 ppb,respectively) (ARDL, 1998).

These studies indicate that off-site groundwater contamination appears limited to areassurrounding Brush Creek and the southern boundary of IAAAP. Current concentrations of off-site RDX-contaminated groundwater near the IAAAP boundary are generally less than 10 ppb(ACE, 1997b,c). Concentrations have been observed to be more diluted with greater distancefrom the installation. Due to natural dilution factors, RDX concentrations in groundwater may decrease further with time.

Potential Human Health Hazards from Past Off-site Exposures

Although not well documented in the administrative record for this installation, the earliestindication of off-site contamination noted in the area south of IAAAP dates to the 1950s. Atthis time, contamination in surface water was noted. Shortly thereafter, the Army firstprovided bottled water and then provided individual household water filtration units to somearea residents to ensure the availability of safe drinking water. Also during this time interval,some area residents hauled water for their domestic animals.

In the early 1970s, contaminant levels had reportedly declined and, in 1973, the Army ceasedto provide funding for the continued use of individual household water filters. Some arearesidents continued to use these filters for a while, but most residents started to use bottledwater for drinking water and cooking purposes. No data are available to quantify the actuallevels of RDX-contamination in drinking water or the time interval(s) that contaminated watermay have been ingested. Thus, ATSDR is not able to evaluate the possible health hazardsassociated with this past episode of off-site contamination. The measures taken by the Armyand the residents themselves during this time period were protective of public health and theingestion of contaminated groundwater was probably minimized or largely eliminated.

In 1985, community residents living along the southern border of IAAAP expressed concernabout potential environmental impacts of disposed wastes and the migration of contaminantsfrom IAAAP into their private drinking water wells adjacent to Long Creek. Suspectingmunitions or radiological contamination (emanating from past AEC activities at IAAAP), theArmy and EPA thoroughly investigated the matter and sampled local groundwater. No organicconstituents were detected and all metals concentrations met regulatory standards in the potablewater consumed by the residents. This, combined with the absence of contaminants at theperimeter monitoring wells on site, indicates that no contamination was emanating fromIAAAP and impacting off-site potable water supplies at the time.

When RDX was detected in private wells in 1992, the Army immediately provided bottledwater to all affected residences. The Army then contracted with the Burlington MunicipalSystem and Rathbun Water Company to connect 154 residences in the area to the public watersupply. Even though most residences were not directly impacted by groundwatercontamination, the Army took preventative measures and conservatively defined the affectedarea as all residences south of the IAAAP, between Brush Creek at the IAAAP's southeasternboundary, to an unnamed tributary south of Line 3A, at the IAAAP's southwestern boundary,south to the Skunk River. Fifteen households in this area declined the Army's offer to connectthem to the Rathbun Rural Water System. Fourteen of these 15 households useuncontaminated private wells. The fifteenth household knowingly chooses to continue to use awell that draws from a contaminated aquifer despite the Army's repeated recommendations to discontinue using this private well water.

To evaluate whether health hazards are associated with exposure to area groundwater, ATSDRestimated the potential exposure doses for adults and children who drank water from affectedwells. To estimate human exposure doses, ATSDR used very conservative assumptionsbelieved to greatly overestimate the levels of actual exposure. These assumptions, ATSDR'smethods, and the estimated exposure doses for ingestion of RDX-contaminated water are provided in Appendix B.

The estimated doses for an adult and a child are less than those associated with adverse healtheffects. ATSDR, therefore, concludes that off-site past exposure to RDX-contaminatedgroundwater via private drinking wells posed no apparent public health hazards.

Concern: Surface Water

Could exposure to RDX or other contaminants in surface water result inadverse human health effects for people exposed to Skunk River, Brush Creek,Spring Creek, Long Creek, and other surface water bodies near IAAAP?

Conclusions

Past activities at IAAAP affected surface water in Brush, Long, and SpringCreeks and some un-named Skunk River tributaries. Other on-site surfacewater bodies have remained uncontaminated by site contaminants.

Historically, TNT may have been the primary contaminant of concern, butcurrently RDX is the most prevalent contaminant in surface water.

It is unlikely that surface water was a public health hazard in the past but,because quantitative historical water quality data do not exist for the IAAAParea, ATSDR concludes that past surface water exposure poses an indeterminate public health hazard.

ATSDR concludes that present and potential future surface water exposure doesnot pose a public health hazard because: 1) contaminant concentrations are toolow to pose a health hazard and/or 2) exposure to the general public is minimal, if it occurs at all.

Discussion

IAAAP property has several streams, rivers, and other surface water bodies. Totaling an areaof approximately 13 acres, 30 ponds and small impoundments are located on the installation(JAYCOR, 1996). The average creek width within IAAAP varies from about 50 to 200 feet. The three primary watersheds draining IAAAP are Brush Creek, Long Creek, and Spring Creek.

Brush Creek runs from IAAAP's northern boundary, through the central part of the base, downto the southeastern corner of the property. It runs through the locations where most activityassociated with facility operations occurs, draining the majority of industrial operations: Lines1, 2, 3, 6, 7, 9, 800, the Line 800 Pinkwater Lagoon, the former Line 1 Impoundment, parts ofLines 4A and 5A, the Pesticide Pit, and the Sewage Treatment Plant. Long Creek flows eastfrom IAAAP's western boundary into Mathes Lake, which is located in the central part of theinstallation. Long Creek surface waters remain uncontaminated. Until 1977, treated surfacewater from Mathes Lake served as IAAAP's primary drinking water source. Spring Creekflows south along the installation's eastern boundary. RDX is the main contaminant ofconcern, although other explosives and some metals have been detected in Brush and Spring Creeks.

In the past, Brush Creek "ran pink" from IAAAP explosives contamination. ATSDR found nostudies or technical reports quantifying this claim, but several documents said that thiscommunity concern about pink water was raised during the World War II era (ACE, 1997b,c). Past employees of IAAAP verified that explosives contamination continued to be dumped intothe Pinkwater Lagoon throughout the 1960s and 1970s. One former IAAAP employee reportedthat "chunks of TNT and Composition B as large as my fist were in the sump water dumpedinto the lagoon" (Public Comment Responses, 1999). This same employee indicated thatsurface water samples may have been drawn from the creeks in the 1960s and 1970s. ATSDRfound no record of these sampling efforts, so it is impossible to conclusively know what causedBrush Creek to run pink. In general, however, LAP operations generally produce pink waterduring the explosive TNT washdown operations when water is used to remove solvents fromthe product. Pink water is a TNT solution that is approximately 99% water with a TNTconcentration of approximately 5 ppm (McCarley, 1998). Because ATSDR could notdetermine the specific nature and extent of IAAAP past contamination, however, ATSDRconcludes that past exposures to on- and off-site surface water pose an indeterminate public health hazard.

Currently, public exposure to contaminated surface waters--defined as surface waters that failto meet ATSDR's drinking water comparison values and health advisory levels--is extremelylimited, if it occurs at all. The primary contaminant in surface water is RDX, with otherexplosives (including TNT) detected in trace amounts. Contaminant concentrations, especiallythose detected in Brush Creek, fluctuate and have not been fully characterized, but publicexposure to these contaminants is limited due to military security measures, perimeter fencing, and natural dilution factors.

There are several water-related recreational facilities on IAAAP and in the immediate areasurrounding the installation, but none of these recreational facilities have been affected bycontaminated surface waters. Mathes Lake (also called Long Lake) is located on IAAAP. Onthe water front area of Mathes Lake, where Long Creek feeds into the Lake, there is a smallscout camp site. A boat ramp is located on the east shore of Mathes Lake that is used byfishermen. South of IAAAP is the Skunk River, which has two boat launch access areas andone small park located on its banks, most of which are located in the area known as Augusta. The Skunk River is used for all types of recreation, such as boating, water skiing, swimming,and fishing. Brush Creek is too small to be suitable for typical recreational activities such asswimming, boating, or fishing, but it may be used for recreational purposes by children. Children only have access to Brush Creek after it leaves IAAAP property.

Based on installation geology and hydrogeololgy, on-site contaminants could be carried off sitevia surface water, primarily Brush Creek and the small unnamed tributaries of Skunk River inthe southwest. Off-site concentrations of explosive contaminants, including RDX, variedwidely among different sampling events. Generally, RDX levels detected in Brush Creeksurface water near the IAAAP boundary remained below 10 ppb. After a rain event in April1995, however, these RDX concentrations reportedly reached 22 ppb. The Army does notcurrently understand the complete extent and role of contributing factors that cause suchsurface water concentration changes, but on-going Brush Creek studies are investigating thesefluctuating concentrations. RDX levels in un-named Skunk River tributaries slightly exceeded2.0 ppb. Public exposure to surface water in Brush Creek and Skunk River tributaries is likelyto occur infrequently and for short durations of time. Incidental ingestion of and/or dermalcontact with such low-level contaminated surface water, if it occurred at all, would not beassociated with adverse health effects. ATSDR concludes that present and potential futureexposures to on- and off-site surface water pose no apparent public health hazard.

Concern: Soil and Sediment

Could exposure to soil and sediment contaminants at IAAAP result in adversehealth effects for employees, residents, or visitors of the installation?

Conclusions

Some IAAAP soils and sediments have been contaminated by military practicesassociated with ammunition LAP operations.

The major sources of contamination at IAAAP occur in enclosed industrialareas or at installation facilities where there is no permitted public access.

ATSDR concludes that soil and sediment contamination at IAAAP poses nopublic health hazards because 1) publicly-accessible areas contain contaminantconcentrations too low to pose health hazards; 2) exposure (past, present, andfuture) to the general public has been prevented; and/or 3) remedial activitieshave reduced or will reduce contaminant concentrations to levels that pose no public health threat.

Discussion

Forty-four sites of known or suspected soil contamination have been identified at IAAAP. Thirty-three of these sites required further investigation under the RI and were thoroughlyevaluated in this Public Health Assessment (Appendix A). Metals and explosives were theprimary contaminants of concern in soils. ATSDR compared on-site metal levels to soilcomparison values, IAAAP background samples, and detection limits to define contamination.

Site investigations reported the most significant contamination at Lines 1, 2, 3, and 3A, theExplosive Disposal Area, the Firing Site, and the Fire Training Pit (Engineered Efficiency1996, 1997). Prior to remediation efforts, two subsites, the Line 1 Impoundment and Line 800Pinkwater Lagoon, were considered to be the greatest sources of explosives contamination atIAAAP. At other sites investigated, soil and sediment contamination was localized, if detectedat all, and generally at low levels (Engineered Efficiency 1996, 1997).

Public access to contaminated sites is restricted and prevented because (in addition to perimeterfencing at IAAAP) secondary fencing and security measures surround almost all industrialareas and installation facilities where soil contamination occurs. Unfenced sites withpotentially-contaminated soil/sediment include the Inert Landfill, Construction Debris Landfill,and Demolition Area. Surface soils at these three sites contain contaminant concentrationsbelow levels associated with health effects and/or are undergoing remedial activities to reducecontaminant concentrations to levels protective of human health. Public exposure to on-sitecontaminated sediments is prevented because the sediments lie underwater, beneath on-sitesurface water bodies. For some of the year, low surface water flows may allow for the publicto walk through the streams, but on-site exposure to sediments appears minimal because on-site visitors are likely to wear shoes or boots and will not regularly be exposed to thesesediments.

Deer hunting is permitted on the installation and at areas surrounding IAAAP, so deer huntersmay have come in contact in the past to contaminated soils at the unfenced sites, specifically atthe Inert Landfill. ATSDR believes that incidental exposure to soil contamination is extremelyminimal, if it occurs at all, for two primary reasons: 1) the amount of time deer hunters spendin contact with on-site contaminated soil is likely to be very brief and will not occur on aregular basis, and 2) the hunters will likely stay in forested areas and their margins, rather thanventure into the open fields or industrial areas where the soil contamination occurs.

Army-approved groups (e.g., the Boy Scouts of America) and trespassers may access forestedand agricultural areas on site, but it is extremely unlikely that they will access contaminatedsites. No contaminated areas are located near the scout camp at Mathes Lake and nocontaminated areas are located near IAAAP's perimeter. No likely exposures are near the InertLandfill or other areas of known soil contamination (Appendix A).

The Army has initiated NTC removal actions to address soil contamination at several areasacross the IAAAP (O&M, 1998; OHM Remediation Services Corp., 1996). The Army isremediating soil contamination even though there is little, if any, public exposure tocontaminated soils, to prevent the potential movement of contaminants to underlyinggroundwater. Remediation sites include the Inert Landfill, the Pesticide Pit, the former FireTraining Pit, explosives-contaminated sumps, and the Line 1 Impoundment and Line 800Pinkwater Lagoon subsites. All major sources of contamination at IAAAP either have been orwill be remediated (e.g., landfill consolidation, capping, bioventing, or soil vapor extraction)(O&M, 1998) (see Completed Soil Actions of the Public Health Action Plan). ATSDRconcludes that past, present, and future exposures to on- and off-site soil and sediment donot pose a public health hazard.

Plant uptake of RDX varies by species and growing conditions. According toan on-site Army study and off-site environmental investigations, the IAAAP crops eaten by humans (specifically corn and soybean) do not appear to bioaccumulate RDX into their leaf, stalk, grain, or root tissues.

Available data indicate that environmental RDX, similar to those levels detectedat IAAAP, does not bioaccumulate in deer tissue. Because deer and cattle areclosely related species, they have similar metabolic processes; therefore, it isequally unlikely for cattle to accumulate explosives in their tissues.

ATSDR was unable to identify any specific public health hazards associated with the consumption of local biota. RDX concentrations detected in local biota are not bioaccumulating at levels expected to affect human health via the food chain (plant-animal-human).

Discussion

Crops in the vicinity of IAAAP may be irrigated with RDX-contaminated water and grow insoil containing RDX (maximum detected concentration of 1.4 parts per million [ppm]). Tobetter characterize the potential for RDX to accumulate in on-site plants, the Army conducted astudy in the summer of 1994 (Center for Environmental Restoration Systems, 1995a). Thisstudy found that the potential exists for RDX to enter the food chain via fruit- and nut-bearingtrees, as well as in locally-grown grains. RDX was found in the shoots and roots of someplants growing on RDX-contaminated soils at sites surveyed at IAAAP. Plant concentrationsof RDX varied greatly by species.

ATSDR examined potential health impacts associated with IAAAP plants consumed by people,specifically corn and soybeans. Only one sampled agricultural area, a small area in onecornfield, contained detectable RDX in the soil. Corn grown in this contaminated soil did notcontain detectable RDX concentrations in its corn leaf, stalk, grain, or root samples. Similarly,corn grown in uncontaminated soil contained no detectable RDX concentrations (Center forEnvironmental Restoration Systems, 1995a). These findings are consistent with other studiesindicating that at relatively low levels of RDX in soil (< 0.3 ppm ) or in irrigation water (< 0.1ppm), RDX does not bioaccumulate in crops (USAEC, 1996). Soybean crops were notsampled at IAAAP, but other studies indicate that soybean and corn bioaccumulate RDX insimilar concentrations (i.e., little or no bioaccumulation at lower soil and water concentrations;bioconcentration factors increase at higher levels of RDX in soil and water) (Checkai andSimini, 1996). Because IAAAP crops are not grown in highly contaminated soil, are notirrigated with highly contaminated water, and the Army study indicates that no RDX isbioaccumulating in corn, ATSDR concludes that local crops are safe for human consumption.

Another community concern addresses the safety of human consumption of venison and beeffrom animals which feed on the installation. Specifically, community members expressedconcern that deer and cattle caught on the installation might be unfit for human consumptionbecause the animals may eat plants containing RDX and/or drink from contaminated surfacewater. Although no IAAAP studies specifically address this issue, ATSDR identified severaldeer tissue studies of explosives uptake conducted at other facilities. According to theliterature, explosives (including RDX) do not bioaccumulate significantly at the concentrationstypically seen in the environment (EPA, 1997; ATSDR, 1996; Whaley and Leach, 1994;Shugart et. al., 1990). At another facility, the Joliet Army Ammunition Plant, with similarcontamination issues, a study found that on-site deer tissue did not contain any detectableexplosives or explosive residues in either deer muscle or deer liver (Whaley and Leach, 1994). Although ATSDR identified no cattle studies, ATSDR expects that RDX levels in beef wouldbe comparable to those found in venison because both cattle and deer are ruminants (belong tothe mammalian suborder Ruminantia) that have similar metabolic processes (ATSDR, 1996). From these toxicologic and ecological studies, ATSDR concludes that deer and cattle residingon IAAAP property are unlikely to contain significant levels of RDX, if any.

ATSDR concludes that past, present, and future consumption of local crops, deer, and cattledoes not pose a public health hazard.

ATSDR identified community health concerns by talking with local citizens, meeting withIAAAP employees, and reviewing IAAAP RAB discussions. ATSDR found that thecommunity's greatest health concerns involve issues pertaining to groundwater contaminationand radiological contamination.4 In the past, local citizens expressed concern about potentiallydeveloping cancer and/or other health problems from exposure to IAAAP-contaminatedgroundwater. Local newspapers printed articles about the reported health problems of a familyliving south of IAAAP. No toxicological studies or health outcome data were ever gathered toverify such public health effects. Based on the concentrations of environmental contaminantsin the vicinity of IAAAP and toxicological information, however, it does not appear thatinstallation-related contaminants can be causally related to public health effects. There is onlylimited exposure, if any, to the environmental contaminants at IAAAP. Adverse public healthimpacts are not likely from the exposures that would reasonably be expected to occur or would have reasonably been expected to have occurred in the past.

ATSDR recognizes that infants and children may be more sensitive to exposures than adults incommunities with contamination in their water, soil, air, or food. This sensitivity is a result ofa number of factors. Children are more likely to be exposed to soil or surface watercontamination because they play outdoors and often bring food into contaminated areas. Forexample, children may come into contact with and ingest soil particles at higher rates thanadults do; also, some children with a behavior trait known as "pica" are more likely than othersto ingest soil and other nonfood items. Children are shorter than adults, which means they canbreath dust, soil, and any vapors close to the ground. Also, they are smaller, resulting in higherdoses of chemical exposure per body weight. The developing body systems of children cansustain permanent damage if toxic exposures occur during critical growth stages. Becausechildren depend completely on adults for risk identification and management decisions,ATSDR is committed to evaluating their special interest at sites such as IAAAP, as part of theATSDR Child Health Initiative. ATSDR has attempted to identify populations of children in the vicinity of IAAAP and any completed exposure pathways to these children.

In the IAAAP area, ATSDR identified several populations of children. Several active schools,day care facilities, and church facilities are all located off site. The closest active school is inDanville, Iowa, which is over 4 miles from IAAAP. Several inactive schools (e.g., the BuenaVista School and Brush College) are located on or near IAAAP, but all these educationalfacilities are located on uncontaminated soil.

None of the identified child populations have been exposed to contaminant levels associatedwith adverse health effects in children. There are no child exposures (past, present, or potentialfuture) to on-site RDX-contaminated groundwater, soil, sediment, or surface water. On-siterecreational facilities, including the scout camp on Mathes Lake, are not associated with anyknown contamination. There is no known contamination associated with off-site soil,sediment, or local biota. As outlined in Appendix B, past exposures to RDX in off-site privatedrinking water wells were at levels below those associated with health effects in children.5

Low-level RDX contamination (generally less than 10 ppb) has impacted off-site surface watersouth and southeast of IAAAP. The maximum detected concentration in off-site surface wateris below drinking water levels associated with adverse health effects in children (Appendix B). No one, however, drinks this surface water. Child exposures are limited to dermal contactand/or incidental ingestion when swimming or playing in the creeks. Exposure is furtherlimited by Iowa's climate; according to local community members, children only swim in thecreeks during Iowa's summer months (ATSDR, 1998). Therefore, surface water exposure doesnot currently pose a public health hazard for children.

It is possible that in the past children were exposed to higher concentrations of RDX and otherexplosive contaminants (e.g.,TNT) in surface water. Surface waters were not sampled duringthe 1950s when off-site creeks ran pink. ATSDR does not believe that it posed any childhealth risks because it is highly improbable that children would have swam or played incontaminated pink waters when abundant uncontaminated surface waters (e.g., Long Creek)were located in the immediate vicinity. Past child exposures would have been further limitedby seasonal swimming due to Iowa's climate. It should also be noted that ATSDR was unableto identify any specific health complaints or symptoms (child or adult) that communitymembers associated with past IAAAP activities. Because, however, this past exposure is notfully characterized and remains unquantifiable, ATSDR concludes that past surface waterexposure poses an indeterminate health hazard for children. For all other exposurepathways, on- and off-site groundwater (past, present, and future), surface water (presentand future), and soil (past, present, and future), ATSDR concludes that these exposures poseno or no apparent public health hazard for children.